单选题 American researchers are working on three antibodies that many mark a new step on the path toward an HIV vaccine, according to a report published online Thursday, July 8, 2010, in the journal Science. One of the antibodies suppresses 91 percent of HIV strains, more than any AIDS antibody ever discovered, according to a report on the findings published in the Wall Street Journal. The antibodies were discovered in the cells of a 60-year-old African-American gay man whose body produced them naturally. One antibody in particular is substantially different from its precursors, the Science study says. The antibodies could be tried as a treatment for people already infected with HIV, the WSJ reports. At the very least, they might boost the efficacy of current antiretroviral drugs. It is welcome news for the 33 million people the United Nations estimated were living with AIDS at the end of 2008. The WSJ outlines the painstaking method the team used to find the antibody amid the cells of the African-American man, known as Donor 45. First they designed a probe that looks just like a spot on a particular molecule on the cells that HIV infects. They used the probe to attract only the antibodies that efficiently attack that spot. They screened 25 million of Donor 45's cell to find just 12 cells that produced the antibodies. Scientists have already discovered plenty of antibodies that either don't work at all or only work on a couple of HIV strains. Last year marked the first time that researchers found "broadly neutralizing antibodies, " which knock out many HIV strains. But none of those antibodies neutralized more than about 40 percent of them, the WSJ says. The newest antibody, at 91 percent neutralization, is a marked improvement. Still, more work needs to be done to ensure the antibodies would activate the immune system to produce natural defenses against AIDS, the study authors say. They suggest three test methods that blend the three new antibodies together in raw form to prevent transmission of the virus, such as from mother to child; in a microbicide gel that women or gay men could use before sex to prevent infection; or as a treatment for HIV/AIDS, combined with antiretroviral drug. If the scientists can find the right way to stimulate production of the antibodies, they think most people could produce then, the WSJ says.

单选题 We can learn from the beginning of the passage that______.

单选题 What is the implication of the antibodies discovered in the cells of the African-American gay man?

单选题 The newest antibody found in Donor 45 reflects a dramatic advance in terms of______.

单选题 According to the study authors, the three test methods are intended to______.

单选题 The passage is most likely______.